When aircrafts (e.g. airplanes) are on the ground, after landing and before takeoff, they are often led from one location to the next in an airport by designated vehicles called tractors or tugs. These vehicles are used to push or pull the aircraft around the airfield. One common example of such aircraft transport is a pushback procedure during which a tractor pushes an aircraft away from an airport gate. Aircrafts are also pushed and/or pulled for various other maintenance purposes.
Tractors dedicated for leading aircrafts often comprise a low profile platform designed in order to fit under the aircraft's underbelly and connect to the aircraft near the aircraft's nose landing gear (NLG) and in some cases under the aircraft's NLG.
While an aircraft is being led (pushed or pulled) by a tractor, steering of the tractor results in a steering-angle between the body of the tractor and the body of the aircraft. Over-steering may occur when the steering-angle exceeds the given mechanical limits and may result in damage to the aircraft.
There is therefore a need in the art for a system and method which enable to monitor the steering-angle, and alert an operator before over-steering occurs.
Published documents considered to be relevant as background to the presently disclosed subject matter are listed below. Acknowledgement of the documents herein is not to be inferred as meaning that these are in any way relevant to the patentability of the presently disclosed subject matter.
U.S. Application Publication No. 2005196256A discloses an early warning system for a tractor operator engaged in towing or pushing an aircraft, and includes two ultrasonic sensors that are used to create a detection area in which the aircraft should be present when the steering-angle is well within a safe range. When one of the detectors fails to detect the presence of the aircraft, then the operator is alerted, before over-steering can occur, in order that corrective action can be undertaken. Accordingly, complex distance-measuring algorithms can be avoided as can the requirement that an aircraft fuselage have a specially modified detection region.
U.S. Pat. No. 5,680,125 discloses that a wheeled vehicle has a source of collimated radiation which directs a beam on a surface of the aircraft having at least two significantly different collimated radiation reflecting areas (e.g. a light material arc bounded by dark material marks). In response to radiation from the collimated beam, or lack thereof, reflected from the surface of the aircraft back to a receiver on the wheeled vehicle, it can be determined if the nose wheel steering-angle is within an acceptable range. Two beam sources and receivers may be provided, and other information-such as the size of the aircraft may also be calculated. An indicator or device for initiating corrective action may be provided to respond to insufficient reflected radiation received by the receiver.